Unify get preferred locations for shuffle in AQE

It has several issues with method `ShuffledRowRDD#getPreferredLocations`.

• it does not respect the config `spark.shuffle.reduceLocality.enabled`, so we can not disable it.
• it does not respect `REDUCER_PREF_LOCS_FRACTION`, so it has no effect if DAG schedule task to an executor who has less data. In worse, driver will take more memory to store the useless locations.